This invention relates to forceps of the rongeur or bone cutting type and more particularly to a rongeur structure which prevents premature ware in the bone cutting surfaces.
It has long been an object in the art to provide simple, inexpensive forceps capable of easy disassembly and cleaning, and most importantly capable of safe and efficient operation. Prior patents issued in this art have proposed possible solutions. Typical of the prior art is the patent issued to De Vilbiss, U.S. Pat. No. 1,040,523, which provides a lever mechanism comprising a handle having two sides arranged to pivot towards one another about a central axis. On extensions of these handle members there is provided a jaw mechanism comprising a first movable jaw arranged to travel within a slot defined within a second movable jaw. Bone seized between the jaws is pulled within the slot as it is cut.
A problem associated with this and other mechanisms in the art is that uncontrolled force is applied to the bone surface surrounding the cutting area, such that possible bone breakage and splintering may occur. If operating near the spinal cord, possible nerve damage may result. Further, bone chips cut from the bone structure are not well contained by the instrument and contamination of the wound may result. Finally, with the pivot placed between the jaw mechanism and the lever handles limited mechanical advantage is available, making the instrument tiring to use. Further, the large force applied to the bone may also be applied across the cutting surfaces which come into contact with each other at the end of the cutting stroke. Such large forces applied across contacting cutting surfaces cause unnecessary waring of the sharp edges.
Accordingly, it is the primary aim of the present invention to provide an approved forcep or rongeur for cutting bone wherein the bone chips, once severed, are safely contained within the instrument and held therein until selectively ejected, and the force applied between meeting cutting surfaces is decreased at the end of the cutting stroke in order to prevent ware thereto.
It is also an object of the present invention to eliminate uncontrolled forces in and about the cutting area to avoid possible bone breakage and splintering beyond the cutting area while utilizing structure which prevents excessive ware on the cutting surfaces.
It is also an object of the present invention to modify the mechanical leverage to provide improved mechanical advantage for the device and to provide better control during operation while utilizing structure which prevents excess ware on cutting surfaces located in the cutting area.